Pregnancy-specific beta 1-glycoprotein (SP1) levels measured by nephelometry in serum from women with vaginal bleeding in the first half of pregnancy.

Pregnancy-specific beta 1-glycoprotein (SP1) levels were measured by nephelometry in sera from 107 women admitted to hospital because of vaginal bleeding in weeks 8 to 20 of pregnancy. The SP1 results were compared with those in single samples from 655 women and serial samples from 9 women with uncomplicated single pregnancies in the same period. The possibility of predicting the outcome of a pregnancy complicated by vaginal bleeding was calculated on the basis of the SP1 level on admission to hospital. In 65% a normal SP1 value predicted continuation of pregnancy, whereas a low SP1 value invariably predicted spontaneous abortion.